The present invention relates to a concrete stone facing machine, its method of operation and the resulting concrete stone block having an irregular rough surface which is chipped to resemble a real stone face.
There has been a need for several decades to develop a machine capable of facing stones by chipping the stone to form a rough surface resembling a real stone. For example, in U.S. Pat. No. 2,867,204, issued on Jan. 6, 1959, there is proposed a machine which is provided with two opposed chisels which are disposed against opposed surfaces of a stone adjacent a face to be roughened. These chisels are impacted by hammers whereby to simulate a conventional method that a mason uses to chip a stone. U.S. Pat. No. 2,912,969, also issued in 1959, describes a stone dressing and planing machine which utilizes a pair of opposed vertically movable, horizontal blades and a pair of vertical blades operated by rams. These pair of blades are actuated in unison, one after the other whereby to square face stone blocks or rubble stones which are used for erecting buildings. This machine is not for chipping a stone to form an irregular rough surface to resemble a real stone face.
More recently, with the advent of paving stones formed from concrete molds, a need has developed to roughen these prefabricated stones to resemble a real stone which has rounded and fragmented edges and surfaces. This is usually done by tumbling the stones in large cylindrical tumblers whereby the stone impacts abrading elements provided on an inner surface of the cylindrical containers as well as impacting one another. This has been a costly and hazardous operation as a percentage of the tumble stones will fragment and then have to be discarded. They are also labour intensive, result in injuries and the operation is very physical requiring shift work of short duration. However, this roughened or abraded process is only superficial on the surfaces and edges of the block and do not deeply penetrate the surfaces. Real stone faces have a deeper and irregular texture which these machines and process cannot achieve.
It is a feature of the present invention to provide a concrete stone facing machine which substantially overcomes the disadvantages of the prior art and meets the needs for production of concrete stones having a projecting irregular front rough surface to resemble a real stone face.
According to a further object of the present invention there is provided a method of forming a projecting irregular rough surface in a face of a concrete stone having opposed flat faces whereby the front face is textured to resemble a real irregular stone face.
According to a still further feature of the present invention, there is provided a pitching blade assembly for use in a concrete stone facing machine whereby to pitch a concrete stone about its periphery to form an irregular rough projecting front face.
According to a still further feature of the present invention there is provided a concrete stone having opposed flat walls surrounding a projecting irregular rough front face resembling a real stone face.
According to the above features, from a broad aspect, there is provided a concrete stone facing machine comprising means to convey a stone having opposed flat surfaces to a pitching station where a predetermined one of said surfaces of said stone is to be pitched to form a deep irregular rough surface to resemble a real stone face. At least one pair of opposed pitching blade assemblies are aligned in a common plane on a respective side of said pitching station. Means is provided to displace each of the pitching blade assemblies towards and away from one another a predetermined distance. Each pitching blade assembly has a plurality of pitching blades secured in side-by-side aligned relationship. Each pitching blade assembly has a forward projecting cutting edge and a securing body portion. A first group of the pitching blades has their cutting edges aligned with a first straight cutting axis which is offset from the cutting edges of a second group of pitching blades and aligned along a second straight cutting axis. The cutting axes are parallel to one another.
The present invention also provides a method of forming a deep irregular rough surface in a face of a concrete stone having flat faces whereby said face is textured to resemble a real irregular chipped stone face. The method comprises the steps of: i) Conveying a concrete stone in a predetermined oriented position to a loading station adjacent a pitching station. ii) Arresting said stone at a predetermined position at said loading station in alignment with said pitching station. iii) Providing at said pitching station two pairs of opposed blade assemblies, one pair being horizontal pitching blade assemblies and another pair being vertical pitching blade assemblies. Each of the pitching blade assemblies have a plurality of pitching blades secured in side-by-side relationship. Each pitching blade has a forward projecting cutting edge and a securing body portion. A first group of the pitching blades has their cutting edges aligned with a first straight cutting axis which is offset from the cutting edges of a second group of pitching blades aligned along a second straight cutting axis. The cutting axes are parallel to one another. The pitching blade assemblies lie in a common vertical plane. iv) Positioning the stone by pusher means to the pitching station with the face to be textured projecting a predetermined distance within the common plane. v) Displacing the pitching blade assemblies simultaneously to cause the pitching blades to move into surrounding, substantially transverse, surfaces of the face a predetermined distance to chip the face to form an irregular rough surface. vi) Discharging the concrete block with the chipped irregular rough surface.
The present invention also provides a pitching blade assembly for use in a concrete stone facing machine to pitch a concrete stone to form a deep irregular rough surface in a face of the stone surrounded by opposed flat surfaces. The pitching blade assembly comprises a blade holder and a plurality of pitching blades secured in side-by-side aligned relationship to he blade holder. Each said pitching blade has a forward projecting cutting edge and a securing body portion. A first group of the pitching blades has a forward projecting cutting edge and a securing body portion. A first group of the pitching blades has their cutting edges aligned with a first straight cutting axis which is offset from the cutting edges of a second group of pitching blades aligned along a second straight cutting axis. The cutting axes are parallel to one another.
The present invention still further provides a concrete stone having opposed flat walls surrounding a deep irregular rough surface resembling a real stone face. The opposed flat walls have, immediately adjacent the deep rough surface, two groups of spaced apart blade indentations aligned along respective straight parallel axes with at least some of the blade indentations being fragmented or partially fragmented.